Field Sobriety Tests 101

Every DUI/DWI attorney you speak with will tell you the same thing: Field sobriety tests are 100% voluntary. So if you find yourself being pulled over by law enforcement and asked to take them, you should know that you are not legally obligated to do and should politely decline.

 

What is the Purpose of Field Sobriety Tests?

 

The reason field sobriety tests are in existence is to help officers in the field gain probable cause to arrest those they suspect of drinking and/or drug use while driving.  They are also used in court by the prosecution as evidence of a person’s impairment while they were driving.  This is because there are actually two charges you face with a DUI, one being guilty per se by virtue of having a blood alcohol content level (BAC) over .08 and above, the other is driving while impaired.  This is to prevent the argument that chronic alcoholics or those with a high tolerance for alcohol cannot be charged because they actually may function perfectly well at the time of driving with a high-level of alcohol in their system.

 

Why Shouldn’t I Cooperate with the Police and Take the Tests?

 

The reason attorneys will advise you not to take the tests, regardless of how much you have had to drink, is that the DUI tests are inherently designed to fail.  For example, if you score 9 out of 10 on the One-Legged Stand test, this is considered a fail and you will be arrested and taken back to the station based on this alone.  Even people with normal balance who are completely sober may not score a perfect ten on this test.  It is up to the officer conducting the test to observe you during the test and score how well you do.

 

As the officer wants to make an arrest every time he stops a car, there is an inherent bias in him observing you and scoring your performance.  Indeed, some officers may not even have the proper training and required certification that they need to administer the tests in the first place.  This is something an experienced DUI attorney will look for when he reviews a case. 

 

How Can an Attorney help me if I Failed the Tests?

 

Many attorneys have themselves become trained and certified to give field sobriety tests so they clearly understand the limitations of the test, and can use these pitfalls to get a defendant off a DUI charge in court.  Even if the attorney is uncertified, he or she should be experienced enough to know the appropriate ways to discredit these tests in court.  This will include conducting a thorough evaluation of the defendant’s mental and physical health history.  A thorough attorney will also ask what kind of shoes the person was wearing at the time of the tests, where the tests took place and so on.  A good attorney will look for any flaw in the way the test was administered, as well as whether the police officer was even certified to perform the test in the first place, in order to discredit and undermine the results of the test in court – or use this as leverage to negotiate a greatly reduced charge for their client.

 

What are the Most Common Field Sobriety Tests?

 

There are 3 standardized field sobriety tests that are accepted as evidence by courts in the United States as they are recognized by the National Highway Transportation Safety Administration (NHTSA).  A brief summary of each can be found below.  There are also other non-standardized tests that officers sometimes use in the field in order to build probable cause for arrest.  Even though the results may not be admissible in court, once the arrest was justified by failure of these tests, the police will then be able to legally obtain blood or breath evidence from someone they suspect is intoxicated at the time of driving.  Blood and breath test evidence is harder to refute and discredit in court (although certainly not impossible) because it is the result of a scientific test, unlike with the field sobriety tests where the officer’s own opinion led to a pass or fail on the test.

 

What are Attention-Divided Tests?

 

All field sobriety tests are divided attention tests, meaning the officer is looking for evidence that the driver is both mentally and physically impaired.  In other words, they want to prove that the driver taking the test cannot fully comprehend and follow simple instructions and perform simple physical tasks at the same time, which likely means they have been using alcohol or other mind-altering substances. Alcohol and certain types of drugs – legal and illegal - cause both physical and mental impairment but it is generally agreed that mental impairment occurs first. So if there is only physical evidence that the defendant is impaired –a good attorney will be able to argue that the defendant could not have been impaired by alcohol as alcohol or drugs at the time of their arrest, because always causes mental impairment first.  Physical impairment can be masked by an individual’s tolerance level, but significant mental impairment always occurs after alcohol consumption at or around the limit of .08 blood alcohol concentration (BAC), which is why this has become the de facto limit in all 50 states.

 

1. Walk and Turn Test

The police officer will give the test in two phases:

 

a. First he directs the driver to stand heel-to-toe, arms down as he or she is listening to the test instructions. The driver is then ordered to take nine heel-to-toe steps in a line, either one that is real, such as a pavement crease, or an imaginary one.  At the end of the 9 steps, they are instructed to turn, and take nine heel-to-toe steps back toward the officer. During the test the police officer is looking for any signs that the driver is struggling with the test.

 

Here are some of the things that an officer will be looking to catch you out on during the test:

 

• inability to balance during instructions
• starting the test too soon
• stopping while walking
• inability to touch heel to toe
• stepping out of the line
• using arms to balance
• loss of balance during the turn or turning the wrong way
• taking the wrong number of steps.

 

If an officer notes just two or more of these occurrences, he will now have probable cause to arrest you. Hence, they are designed to fail. Even a stone-cold sober person would have trouble performing this test, if for example they happened to have bad balance, be significantly overweight, be particularly nervous or anxious over the fact they are being observed by a police officer, be extremely fatigued, were wearing shoes that made it difficult to touch heel to toe, the road was uneven, and so on.

A good DUI/DWI attorney will be able to challenge the results of a walk-and-turn test in court based on some or all of these factors.  If the attorney can successfully argue that the police did not have probable cause to arrest the party based on the result of this test, and this test only, then the case will have to be dismissed. 

 

2. Horizontal Gaze Nystagmus Test

Horizontal gaze nystagmus (HGN) is an involuntary movement or jerking of the eyes as they follow a line or moving object from side to side.  The more alcohol a person has consumed the sooner and more frequently the eyes will jerk as they follow the line.

The officer administers the test by asking the person to follow the tip of a pen while keeping their head totally still. The officer will look at how smoothly the eyes move, and how much jerking they are doing as they move until they reach their farthest point, and whether there was any movement of the head.  Each of these factors is counted by the officer in each eye.  If he counts four out of six, he will conclude that it is very likely the person taking the test has a BAC above the legal limit.  He will then arrest the person for DUI.

This test, like the others discussed, has a high level of innate inaccuracy.  For example, several factors other than alcohol consumption can cause an involuntary jerking of the eye.  Certain eye or head injuries or illnesses can cause the same effect, as can certain prescription and illegal drugs – although you can of course still be arrested for driving under the influence of these (see Drugged DUIs).

An experienced DUI/DWI attorney will take a thorough inventory of their client’s mental and physical health to look for any evidence that can explain why they failed the HGN test.  Similarly, if there were errors in the way the officer conducted the test, for example, through a window or with the driver’s head at an angle, this can further discredit or completely invalidate the test results.

 

3. One-Leg Stand Test

During this test, the officer will tell the person taking the test to stand with feet together and arms down to their side while they listen to the test instructions. The officer will tell the driver to raise one leg six inches with their foot parallel to the ground. The person will then need to count “One thousand one, one thousand two” and so on while staring at his raised foot until the officer tells them to stop. The driver must stand on one leg for 30 seconds.

The officer is looking for four signs of impairment during the test:

 

• swaying while balancing
• using the arms to balance
• hopping on one foot
• putting the foot down three or more times during the test

 

Once the officer observes two or more signs he will decide the person is over the limit and arrest the person for DUI.

As with the other tests – there are is an inherent error in concluding that failure in this test automatically means that a person has been drinking alcohol or using mind-altering drugs.  For example, people with back or leg injuries, individuals with inner-ear disorders or other balance problems, people over 65, and those who are overweight all might find standing on one leg for 30 seconds difficult. Uneven ground or high-heeled shoes could also lead to a false-positive in this test.

A good attorney will be able to take apart the prosecution’s case piece by piece and either look for one large hole in it, or find lots of smaller ones.  The results of any field sobriety tests performed are just one aspect of the case, but a very important one: if the attorney can successfully discredit the field sobriety test results then it could follow that the defendant was arrested without sufficient probable cause and so any other evidence gained after the arrest – breath and blood tests for example - is not admissible into court. Without blood and breath evidence showing an alcohol level over .08, the case will more than likely be dismissed. 

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